UITabBar images visible on simulator, disappear on the device

Question

in an iPhone app, I have a UITabBar with three tabs. One has a system image, two more have custom images. These are PNGs, 30x30, palette-based, mostly transparent. These images show up fine in the simulator, but on the device, all I see is a grey gradiented square on a tab. The shapes on these images are grey to begin with, but they do show up as expected on the simulator.

Any ideas, please?

Answer 1

The image should be white on transparent. It's in the UI design guide. In my case, it was grey on transparent. Simulator forgives that, the device does not.